Social and Internet traffic analysis is fundamental in detecting and defending cyber attacks. Traditional approaches resorting to manually defined rules are gradually replaced by automated approaches empowered by machine learning. This revolution is accelerated by huge datasets which support machine-learning models with outstanding performance. In the context of a data-driven paradigm, this article reviews recent analytic research on cyber traffic over social networks and the Internet by using a set of common concepts of similarity, correlation, and collective indication, and by sharing security goals for classifying network host or applications and users or Tweets. The ability to do so is not determined in isolation, but rather drawn for a wide use of many different network or social flows. Furthermore, the flows exhibit many characteristics, such as fixed sized and multiple messages between source and destination. This article demonstrates a new research methodology of data-driven cyber security (DDCS) and its application in social and Internet traffic analysis. The framework of the DDCS methodology consists of three components, that is, cyber security data processing, cyber security feature engineering, and cyber security modeling. Challenges and future directions in this field are also discussed.
This article is concerned with platooning control of connected automated vehicles. A novel parameter-varying zeroing neural network-based approach is proposed for vehicles to track a virtual signal, while maintaining a desired distance between every two consecutive vehicles. Specifically, distributed parameter-varying observers are first designed to track the virtual signal. Then by using the observers and constructing a nonlinear manifold, a parameter-varying finite-time controller is developed to achieve the platooning control. The proposed parameter-varying controller has advantages of both fast response and disturbance rejection. Finally, numerical examples of five vehicles under different communication graphs are provided to demonstrate the effectiveness of the proposed controllers.
This paper deals with the problem of distributed fault detection for discrete-time sensor networks subject to randomly switching sensing topology. The system dynamics and sensing topology are modeled by a discrete-time Markov chain with incomplete transition probabilities. Each sensor node can effectively communicate with certain neighboring sensors, and randomly switch among finite sensing modes via the Markovian switching rules. The process or the time at which the sensing topology changes does not need to be known a priori. The Kronecker product is adopted to realize the decoupling between the specifical sensor node and its underlying neighboring nodes. By means of the Lyapunov functional approach and an improved free weighting matrix technique, stochastic analysis and design results on distributed fault detection, in terms of a set of linear matrix inequalities (LMIs), are then presented in the simultaneous presence of incomplete transition probabilities, randomly switching sensing topology, uncertain network-induced delays and accumulated data packed dropouts. A simulation example is finally provided to illustrate the effectiveness of the developed theoretical results.
This article is concerned with bipartite consensus tracking for second-order multiagent systems with signed directed graphs. A time-varying function-based preset-time approach is proposed to realize the convergence in predetermined time. First, a class of time-varying functions with generalized properties are presented. Second, two time-varying function-based auxiliaries and a corresponding manifold are constructed. Under a structurally balanced and strongly connected graph, a time-varying function-based controller considering the neighboring state is proposed to guarantee that the system trajectory is constrained on the manifold such that bipartite consensus tracking is achieved in preset-time. Third, for first-order multiagent systems, a preset-time controller is further developed with simplified design. Finally, numerical examples are provided to demonstrate the effectiveness of the proposed controllers.
No abstract is provided for this article.
This paper is concerned with network-based control for an offshore steel jacket platform subject to nonlinear wave-induced force. A network-based dynamic model of the offshore platform is presented and a network-based state feedback control scheme is developed to reduce the internal oscillations of the offshore platform. Then the effect of a network-induced delay on the control performance of the offshore platform is investigated. It is found through simulation results that (i) the network-based state feedback controller is of a smaller gain in the sense of Euclidean norm than the state feedback controller without network setting, which means the network-based state feedback controller requires less control force; and (ii) the network-induced delay is of the positive effect on state feedback control of the offshore platform.
Investigates the controller synthesis of uncertain linear time-delay systems. Stabilizability criteria are derived based on a discretized Lyapunov functional approach. A controller design method is developed. Numerical examples show that the results using the proposed method are less conservative than some existing ones.
This paper is concerned with network-based static output feedback tracking control for a class of nonlinear systems that can not be stabilized by a static output feedback controller without a time-delay, but can be stabilized by a delayed static output feedback controller. For such systems, network-induced delay is intentionally introduced in the feedback loop to produce a stable and satisfactory tracking control. The nonlinear network-based control system is represented by an asynchronous T-S fuzzy system with an interval time-varying sawtooth delay due to sample-and-hold behaviors and network-induced delays. A new discontinuous complete Lyapunov-Krasovskii functional, which makes use of the lower bound of network-induced delays, the sawtooth delay and its upper bound, is constructed to derive a delay-dependent criterion on H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> tracking performance analysis. Since routine relaxation methods in traditional T-S fuzzy systems can not be employed to reduce the conservatism of the stability criterion, a new relaxation method is proposed by using asynchronous constraints on fuzzy membership functions to introduce some free-weighting matrices. Based on the feasibility of the derived criterion, a particle swarm optimization algorithm is presented to search the minimum H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> tracking performance and static output feedback gains. An illustrative example is provided to show the effectiveness of the proposed method.
This paper is concerned with the observer-based event-triggered control for a continuous networked linear system subject to denial-of-service (DoS) attacks, where the attacks are launched periodically to block the data transmission in control channels. First, a new observer state-based resilient event-triggering scheme is developed in the presence of DoS attacks. Second, a novel event-based switched system model is established by considering the effect of the event-triggering scheme and DoS attacks simultaneously. By virtue of this new model combined with a piecewise Lyapunov-Krasovskii functional method, the sufficient conditions are derived to guarantee exponential stability of the resulting switched system. It is shown that the proposed results can establish a quantitative relationship among the launching/sleeping periods of the attacks, the event-triggering parameters, the sampling period, and the exponential decay rate. Third, criteria for designing a desired observer-based event-triggered controller are provided and expressed in terms of a set of linear matrix inequalities. Finally, an offshore structure model is presented to illustrate the efficiency of the developed control method.
This paper is concerned with event-triggered dissipativity of interconnected stochastic systems, where data transmission from one subsystem to the other is completed via a communication network. A novel distributed discrete event-triggered transmission scheme is proposed to determine whether or not the sampled data should be transmitted. Under this scheme, a new event-triggered dissipative control protocol is proposed by introducing event-triggered mechanisms and a zero order holder to deal with network-induced delays. The networked interconnected stochastic system will be modeled as a stochastic system with an artificial delay. For the closed-loop stochastic system, a novel discontinuous Lyapunov functional is constructed to use the sawtooth structure characteristics of the artificial delay. Based on this discontinuous Lypuanov functional, a simplified and efficient dissipativity condition for the networked interconnected stochastic systems is derived and the corresponding controller design method is proposed. Finally, a superheated steam system is employed to illustrate the effectiveness of the obtained results.
This article provides new delay-dependent stability criteria for linear systems with interval time-varying delays. With a new Lyapunov–Krasovskii functional constructed, a tighter upper bound of its derivative is estimated. The resulting criterion has an advantage over some existing ones in the literature due to the fact that it involves fewer matrix variables and is less conservative, which is established theoretically. Two numerical examples are given to demonstrate the reduced conservatism of the proposed results.
This note is concerned with the problem of parity space-based fault estimation for linear discrete time-varying systems. The design of parity space-based fault estimator is formulated as to find a minimum for a matrix quadratic form. It is shown that the minimum provides a unified solution to the fault estimation problem with different design criteria, such as the performance indices of maximum singular value and Frobenius-norm. A necessary and sufficient condition for the minimum is derived and an analytic solution to the parity space-based fault estimator is obtained. Numerical examples are given to show the effectiveness of the proposed method.
This article is concerned with the problem of distributed prescribed finite-time observer design for a strictfeedback nonlinear system with external disturbance. The purpose is to reconstruct the unavailable system state based on a group of distributed observers, where each of them can only receive at most 1-D output measurement from the system. First, in the absence of disturbance, a new distributed prescribed finite-time observer featuring time-varying gains is constructed and designed under the assumption of joint observability. It is analytically proved that for any prescribed instant independent of system initial conditions and other design parameters, the obtained distributed observer can guarantee not only the asymptotic convergence to zero of the state error between each observer state and the system state at this prescribed instant but also the definite zero-state error after this prescribed instant. Second, a distributed prescribed finite-time bounded observer is delicately proposed to account for the presence of external disturbance in the system dynamics. It is shown that the state error can be bounded by an arbitrarily positive constant after a prescribed instant. Finally, a numerical example and an electromechanical system are presented to demonstrate the effectiveness of the proposed results.
This paper investigates the problem of the stabilization of uncertain time-delay systems containing a saturating actuator. The Lyapunov-Krasovskii technique is employed to analyse the stability robustness for the uncertain closed-loop system which is based on a state observer. Some sufficient criteria addressing the robust stabilization of such systems are proposed. These conditions are shown to be less restrictive than those given by Han et al. (1998) and So et al. (1989).
This paper is concerned with network-based leader-following consensus for a distributed multi-agent system. A network-based consensus control protocol under a directed graph is proposed. With this protocol, each agent in the distributed multi-agent system can be remotely controlled via a communication network. A new delay-dependent stability criterion for an error system is derived by constructing a novel Lyapunov–Krasovskii functional with digraph information. Then, employing this stability criterion, a delay-dependent sufficient condition for the existence of network-based consensus controllers, which ensure that the following-agent’s states can reach an agreement on the leader’s state, is formulated in terms of linear matrix inequalities. A numerical example is given to illustrate the effectiveness of the obtained results.
